1. Field of the Invention
The present invention relates to an air intake device for regulating airflow in an air intake passage of an engine. More particularly, the present invention relates to a vehicular throttle body configured to generate turbulent airflow in a stream of incoming intake air flowing into a cylinder of the engine.
2. Description of the Background Art
There is known a vehicle which is provided with an engine, having air intake ports communicating with an air intake passage and which route air into a cylinder of the engine via a throttle body having a throttle valve pivoting around an axis transverse to a central axis of the air intake passage of the engine, and controlling an intake air amount. For example, Japanese published patent application JP-A 2005-42655 describes a vehicle having two throttle valves, in which a pivot shaft center of a first throttle valve, disposed on an upstream side, intersects with a pivot shaft center of a second throttle valve disposed on a downstream side, when viewed in a longitudinal direction of an air intake passage. According to the structure described in this reference, it is possible to produce a swirl in incoming intake air supplied to a cylinder from one of the air intake ports, thus making it possible to improve a combustion state.
However, in the conventional structure described in the above reference, an air intake system having two throttle valves is required, so that a wide space for layout of the air intake system is required, and the number of parts is increased. In addition, since separate coordinated controls are required for each of the two throttle valves, there is a problem that control of the two throttle valves becomes complex.